block: move ->make_request_fn to struct block_device_operations

The make_request_fn is a little weird in that it sits directly in
struct request_queue instead of an operation vector.  Replace it with
a block_device_operations method called submit_bio (which describes much
better what it does).  Also remove the request_queue argument to it, as
the queue can be derived pretty trivially from the bio.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/Documentation/block/writeback_cache_control.rst b/Documentation/block/writeback_cache_control.rst
index 2c752c5..b208488 100644
--- a/Documentation/block/writeback_cache_control.rst
+++ b/Documentation/block/writeback_cache_control.rst
@@ -47,7 +47,7 @@
 may both be set on a single bio.
 
 
-Implementation details for make_request_fn based block drivers
+Implementation details for bio based block drivers
 --------------------------------------------------------------
 
 These drivers will always see the REQ_PREFLUSH and REQ_FUA bits as they sit